Generally, an electric power system implements three primary functions:                generation of electrical power by any of several mechanisms such as burning fossil fuels (e.g., coal, oil or natural gas), nuclear fission, hydroelectric turbines, wind turbines, solar photovoltaic panels, etc.;        transmission of electrical power, typically over long distances at high voltages, from sources of generation to points of distribution such as substations. Sub-transmission may further bridge between transmission and distribution voltages; and        distribution of electrical power, typically over relatively short distances and at relatively lower voltages, from points of distribution such as substations to end customers.        
Electric power system operators, such as electric distribution utilities, regional transmission operators, independent system operators and others, are tasked with maintaining an electrically stable real-time balance between electricity supply and demand. This is difficult to achieve because demand for electricity fluctuates unpredictably, future supply may diverge from actual demand, and unexpected events, such as accidents or equipment failures, may cause unplanned outages of unknown scope and duration.
Emerging clean, but-intermittent power resources, such as wind and solar power, may help reduce the burning of fossil fuels, which produces greenhouse gas emissions and other toxic pollutants. Accordingly, deployment of such clean electric power sources may increase in the coming years. Added to traditional sources of unpredictability in the electric power system, such intermittent resources may exacerbate the problem of maintaining an electrically stable real-time supply-demand balance.
Electric energy storage offers key benefits for utilities and other grid operators, including firming of wind and solar power to address the intermittency of these power sources. Other benefits of electric energy storage include improved reliability, outage backup, volt/VAR control, frequency regulation and system upgrade deferral.
Electric utilities and grid operators view energy storage as highly promising but lacking key qualities such as (i) scalability, which is required to address a wide range of applications, from meter to substation, with common technologies and protocols; (ii) interoperability, which is required to deliver flexible, multi-vendor systems; (iii) modularity, which is required for exchange, upgrade and expansion of system components; and (iv) cost-effectiveness, which is necessary to compete against other carbon polluting alternatives. Because current energy storage products lack modularity, scalability and interoperability, primary suppliers (e.g., battery manufacturers) cannot easily serve primary customers (e.g., electric utilities), thus increasing the cost and availability of energy storage products and limiting market development for all.
Accordingly, these gaps open an opportunity for a new, multi-vendor approach to energy storage, delivering battery ‘storage appliances’ built from optimized storage, power conversion and control components. In this new ecosystem, customers can choose best-of-breed components and upgrade, exchange, or re-use individual system elements as needs change or new technologies emerge. Thus, an energy storage architecture that was designed to enable customers to choose components that best suit their application, and upgrade, maintain or expand the system based on changing needs or new technologies, would be a significant advancement for energy storage, and the efficiency and availability of intermittent clean energy sources.